MechChem Africa April 2020

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Hans (MJ) Strydom talks about the history of breath analysis in themedical profession and the role of calibrationmixtures fromAfrox Special Products in ensuring the accuracy of a diagnosis. Breath analysis: from smelling breath to sophisticated diagnoses

H ippocrates, the father ofmedicine, is credited as being the first to realise that the smell of a person’s breath could be used to establish what was wrong with them. He expected his students to be able to associate the sweet smell of rotten apples in a patient’s breath with diabetes, and a fishy, urine-like smell as an indicator of kidney failure. As science and technology advanced, Lavoisier, the father of chemistry, began the processofsystematicallyanalysingthechemi- cal constituents of gases. He was the first to recognise and name oxygen and the role it plays in combustion reactions. That led to his discovery of carbon dioxide in the air we breatheout,oneoftheproductsofrespiration in which glucose and oxygen are turned into water, carbon dioxide and ATP – the organic energy carrier that drives muscle movement and intracellular energy exchanges. The most commonly known breath analy- sis test of today is the breathalyser test, used to quickly determinewhether a driver is ‘over the limit’ and therefore legally incapable of driving a vehicle. It is increasingly common for all employees andvisitors to safety-critical worksites to be breathalysed, whether they are driving or not. The test measures the percentage of

alcohol in the breath a person exhales. This is used to accurately determine the amount of ethanol (CH 3 -CH 2 -OH) that is being carried in theblood. The accuracyof today’s breathalys - ersmeans that the readings areacceptable for prosecution, but a confirming blood test used to be (and sometimes still is) required. This principle, that the constituent gases or volatile organic compounds (VOCs) that we breathe out can be directly traced to substances in our blood, is true of all breath analysis equipment. During the latter part of the nineteenth century, Linus Pauling’s milestone discovery of 250 unique substances present in exhaled breath offered promising insight into breath testing possibilities. In the 1970s the concept of lactose intol- erance (LI) was evaluated using a hydrogen breath test. Newcomer and his associates studied poor lactose absorption by analysing breath for hydrogen (H 2 ) and CO 2 . H 2 was found to be elevated in lactose intolerant people, while CO 2 values were below normal inmost patients. The researchers determined that ‘measurement of breath hydrogen is sensitive and specific, and does not require Hydrogen breath tests and gastroenterology

ally produce hydrogen gas on fermentation of their carbohydrates. Bacteria can only do this when dietary carbohydrates are not absorbed in the small intestine and, instead, stay as undigestedmaterial travelling into the large intestine. Though some of the hydrogen gas pro- ducedby thebacteria is expelled as flatulence or in making other molecules, most of the gas is absorbed across the lining of the large intestineintothebloodstream.Thegasisthen transported to the patient’s lungs, exchanged into the airways of the lungs and breathed out. The levels of hydrogen gas in the breath can therefore be use to determine if and how much bacterial fermentation is occurring in the bowel. Hydrogen breath tests are, therefore, specific and sensitive diagnostic tests that can be used to either confirmor eliminate the possibility of carbohydrate malabsorption or SIBO in patients. The breath testing proce- dure is simple, reproducible and safe, an ideal substitute for more invasive, uncomfortable and expensive techniques traditionally used in gastroenterology. Afrox has a key role to play inmaintaining the accuracy, validity and credibility of breath test results from the equipment being use by gastroenterologists. The instruments are required to measure very small differences in H 2 concentration and each system has to be calibrated before being used on patients. The calibration procedure requires the use of a high quality calibration gas mixture containing 20 ppm of H 2 in otherwise uncon- taminated clean air. Gases such as these are available through Afrox Special Products, which provides precision gas solutions for optimum accuracy and control in specialised medical and laboratory applications. q

ethanol or isotopes’ and argued that it would be a ‘most suitable test for population screening for lactase deficiency’. Bond and Levitt then went on to use a breath H 2 test to conclude that some disaccharide sugars remain ‘unbroken and unabsorbed’ in the small intestine due to incomplete digestion. Many patients with diges- tion disorders are unaware of the relationship between diet and the symptoms they present. These include abdominal pain, bloating, flatulence and altered bowelmovements (diarrhoeaand constipation), irritablebowel syn- drome or Coeliac/celiac disease. Such patients may have undiag- nosed carbohydrate malabsorp- tion or SIBO (Small Intestinal Bacterial Overgrowth). Bacteria in the bowel gener-

Afrox, the leading supplier of atmospheric gases in Southern Africa, also offers a range of medical and laboratory gas solutions through Afrox Special Products.

32 ¦ MechChem Africa • April 2020